The use of caul screens in fibreboard, particleboard and oriented strand board (hereinafter collectively referred to as “(OSB)” manufacturing is well known. Caul screens are semi-rigid or flexible woven metal mesh screens having a pore size of 0.1 to 0.3 mm. The screens are used as a backing layer to convey heat activated resins together with wood fibers and other cellulose strands into a hot press. The press is then operable to compress and fuse the fibrous materials with the resins into a fiberboard/oriented strand board panel. Following formation, the panel is separated from the screen and trimmed. Any screens which thereafter remain undamaged are then cleaned for further use.
In conventional OSB panel manufacturing systems, the cleaning of caul screens is typically performed manually, by washing the screens using hand-held pressure washers to dislodge any debris which has accumulated thereon. Conventional manufacturing systems suffer the disadvantage in that the manual pressure washing of screens is both labour intensive and inefficient. Hand-held pressure washers typically operate to produce a discharge spray from a single outlet nozzle which is formed with an aperture diameter of 1 to 2 mm. As a result, the pressure of the cleaning fluid stream as it leaves the nozzle is comparably low, often providing an output stream of water at pressures as low as of 250 psi or less. The lower water pressures are often insufficient to effect penetrating of the cleaning fluid through smaller sized mesh apertures. This problem is particularly acute where water alone is used as a cleaning fluid, and without the benefit of surface tension reducing surfactant additives. As a result, while manual pressure washing may achieve partial cleaning of the face surfaces of a caul screen, it is frequently ineffective in dislodging resins and/or other debris from within the mesh openings themselves.
In addition, the applicant has appreciated that the manual pressure washing of caul screens requires comparatively higher volumes of cleaning fluids. In the case of water, these volumes may exceed a flow rate of five gallons per minute. The discharge of excess water may disadvantageously result in conveyor belt or pulley slippage, or other unintentional wetting and/or lubrication of system components.